I never thought changing out your brake fluid would make such a big difference in the feel of your brakes. The rear brake pedal on my 2018 Gold Wing had gotten really spongy feeling, and I actually had to push the pedal down quite far just to get the brake to engage. After the fluid change the rear brake pedal and front brake lever feel had really firmed up. I also had the brake fluid, and the hydraulic clutch fluid on my Superhawk changed, which also made a noticeable difference...
Change your brake fluid
- Thread starter grampi
- Start date
I just did that to my Suzuki. Brake feel didn't change but the system should last longer. Old fluid was nice amber, clear color but it was 12 years old. Just makes sense to change ALL the fluids in your vehicles.
Try it on your car. You’d really be surprised how much it changes. I do my Harleys once a year so I don’t really notice much, but to me it’s cheap insurance.
Another thing that can make a big difference in braking effectiveness on older bikes is changing the rubber hoses. Well, they're probably not really rubber in the strictest sense of the word, but the flexible sections of the brake hose, especially on the front if the lines are relatively long.
On older bikes as the hose deteriorates it begins to swell or expand more under the normal pressure of applying the brakes. This is all force that is not making it to the brake caliper. In really bad cases you can see it in the hose if you look carefully.
The best front brake hose I ever put on a motorcycle was a small-diameter hydraulic hose off a Massey Ferguson tractor. It held up for decades and the improvement in the braking was remarkable. I'm not recommending that anyone do this, it's just by way of illustration or example.
Changing the fluid regularly is good, changing the hoses occasionally is good, and another often overlooked maintenance item is if it's a floating caliper make sure the pins are free in the bushings. I can't recall how many braking problems I have fixed with a few taps of a plastic or rubber mallet. A careful application of the right lubricant on those pins is a good idea, especially if you take your bike to the car wash.
And speaking of "wash," getting the brake dust and road grime out of the calipers a few times a year is never a bad idea.
The braking on a motorcycle tends to deteriorate ever so slightly over time from all of these factors, it happens gradually so we don't necessarily notice it, and then one day when we really need the brakes to work right, they don't.
Good post. Glad you brought this up.
Understanding Brake fluid
DOT 3 DOT 4 and DOT 5.1 are Glycol based brake fluids whereas DOT 5
are Silicone based... Glycol based fluids are designed to signal
moisture contamination by changing color... the fluid will start to
turn golden, then light brown, then dark brown indicating that it has
absorbed progressively more moisture. Eventually, if left unchanged
beyond the recommended service interval, the fluid will become dark
and yukky, indicating high amounts of water absorption and thus badly
contaminated fluid... user friendly Glycol based fluids also reduce
the effect of both corrosion and compressibility because it is not
only designed to accept significant amounts of moisture, but even to
neutralize it by dispersing this moisture evenly throughout the
system, thus preventing its concentration in any one area...
Boiling point of Glycol based brake fluids
DOT 3 205 °C (401 °F)
DOT 4 230 °C (446 °F)
DOT 5.1 270 °C (518 °F)
DOT 5 Silicone based fluid will not turn color to signal moisture
content...
Boiling point of Silicone based brake fluids
DOT 5 260 °C (500 °F)
If you wish to use the latest in Glycol base fluids then its DOT 5.1
Note: DOT 5 silicone was created at the request of the military for
use in vehicles that are required to be parked for years at a time and
be ready for deployment. Harley-Davidson used DOT 5 until a decade ago
because it would not negatively affect paint but currently specifies
DOT 4 or 5.1
WARNING: Dot 5.1 glycol (yellow) and Dot 5 silicone (purple) will not mix.
Boiling points
Moisture Contaminated Glycol fluids...
Dot 5 versus Dot 5.1 they do not mix...
Motul 5.1
DOT 3 DOT 4 and DOT 5.1 are Glycol based brake fluids whereas DOT 5
are Silicone based... Glycol based fluids are designed to signal
moisture contamination by changing color... the fluid will start to
turn golden, then light brown, then dark brown indicating that it has
absorbed progressively more moisture. Eventually, if left unchanged
beyond the recommended service interval, the fluid will become dark
and yukky, indicating high amounts of water absorption and thus badly
contaminated fluid... user friendly Glycol based fluids also reduce
the effect of both corrosion and compressibility because it is not
only designed to accept significant amounts of moisture, but even to
neutralize it by dispersing this moisture evenly throughout the
system, thus preventing its concentration in any one area...
Boiling point of Glycol based brake fluids
DOT 3 205 °C (401 °F)
DOT 4 230 °C (446 °F)
DOT 5.1 270 °C (518 °F)
DOT 5 Silicone based fluid will not turn color to signal moisture
content...
Boiling point of Silicone based brake fluids
DOT 5 260 °C (500 °F)
If you wish to use the latest in Glycol base fluids then its DOT 5.1
Note: DOT 5 silicone was created at the request of the military for
use in vehicles that are required to be parked for years at a time and
be ready for deployment. Harley-Davidson used DOT 5 until a decade ago
because it would not negatively affect paint but currently specifies
DOT 4 or 5.1
WARNING: Dot 5.1 glycol (yellow) and Dot 5 silicone (purple) will not mix.
Boiling points
Moisture Contaminated Glycol fluids...
Dot 5 versus Dot 5.1 they do not mix...
Motul 5.1
After years of shunning this fluid change as OTT, I have become a advocate of "change every two year" policy.
It's not only the preformance which is affect which you may or may not fell but also corrosion to the internal parts of the system.
For my latest change on car & bikes, DOT 5.1 was used and the improvement in performance improvement in all vehicles was amazing. And the ABS on my car is much less trigger happy
It's not only the preformance which is affect which you may or may not fell but also corrosion to the internal parts of the system.
For my latest change on car & bikes, DOT 5.1 was used and the improvement in performance improvement in all vehicles was amazing. And the ABS on my car is much less trigger happy
Changing brake fluid on motorcycles is so important on a scale of importance that many have no clue how important!
Most all manuals state every two years. Brake systems on bike are small, water saturated brake fluid boils under heavy use, vapor lock occurs = loss of brakes.
I know, it happened to me in the mountains on my Yamaha Star 1300 at the time, wife on the back. Had no idea why I lost my rear brakes coming down a mountain, didn't know what was going on, front brakes still working but didnt know if they would keep working, REAL steep mountain, no place to try to pull off, saw my life flash in front of my eyes, almost in tears that I might crash and harm my wife on the back.
Made it to the bottom but it seemed like an eternity getting there, minutes later rear brake started working again, it was then, buried in the manual was to regularly change brake fluid. I was soooo pissed this important matter was so hard to find in the manual because I am a maintenance freak. I changed the brake fluid, problem solved.
I strongly suggest to use the recommended rbake fluid and NEVER 5.0 Silicon brake fluid unless you have one of the rarest of rare bikes or extremely rare car that require it. 5.0 does not absorb water and can pool in the system, also more corrosive prone.
Most all manuals state every two years. Brake systems on bike are small, water saturated brake fluid boils under heavy use, vapor lock occurs = loss of brakes.
I know, it happened to me in the mountains on my Yamaha Star 1300 at the time, wife on the back. Had no idea why I lost my rear brakes coming down a mountain, didn't know what was going on, front brakes still working but didnt know if they would keep working, REAL steep mountain, no place to try to pull off, saw my life flash in front of my eyes, almost in tears that I might crash and harm my wife on the back.
Made it to the bottom but it seemed like an eternity getting there, minutes later rear brake started working again, it was then, buried in the manual was to regularly change brake fluid. I was soooo pissed this important matter was so hard to find in the manual because I am a maintenance freak. I changed the brake fluid, problem solved.
I strongly suggest to use the recommended rbake fluid and NEVER 5.0 Silicon brake fluid unless you have one of the rarest of rare bikes or extremely rare car that require it. 5.0 does not absorb water and can pool in the system, also more corrosive prone.
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I agree with changing the brake fluid on motorcycles every two years. Cars can get away with old brake fluid, but motorcycles are a lot more sensitive.
The systems hold very little fluid, the calipers are aluminum and conduct the heat very well to the fluid and it is all exposed to the elements, making water contamination a lot easier.
The systems hold very little fluid, the calipers are aluminum and conduct the heat very well to the fluid and it is all exposed to the elements, making water contamination a lot easier.
Another thing I didn't know about, the guy who changed my fluid said that keeping an eye on your fluid level is very important. He said if the fluid level drops, it's a sign that your pads are wearing (as long as the system isn't leaking). A mistake many people make is adding fluid to bring it back up to the full mark when they see it's low, then they'll replace their worn pads, and now there's too much fluid in the system. He said this can cause the brakes to lock up. Another good bit of info to know...
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I do top it off. Just have to remember to let some out especially when doing 4 calipers. A rookie mistake I made when flushing is I would start at rear right. Bleed it.
Add fluid. Move to driver rear. I never forced clean fluid out the right rear. Dumb.
What was stupid is sure I bled the rear right and forced dirty fluid out. I should have forced clean fluid out. DOH!
Correct way is remove as much as possible, refill with clean. Now bleed rear right. Maybe more than 1x. After that, keep refilling with clean and force it out rear left, front right, front left….at least on the BMW if any part is removed, they say an automated bleed first is needed, doubling the work and laptop or scan tool needed…
Better late than never.
If not canle operated, don't forget to do the clutch hydraulics too.
I do it every few years on all my vehicles.
when i was racing a full season...i was changing the brake fluid after every race.
i also use a mighty vac
and ive used motul 5.1 for 20 years now
i also use a mighty vac
and ive used motul 5.1 for 20 years now
Some cars, like my 2014 Mazda 3, use the brake fluid for the hydraulic clutch - same system & reservoir. So when I service the brakes (flush fluid & bleed) I also bleed the clutch.
Other cars, the clutch system is separate requiring its own fluid flush & bleed.
I've been using Motul RBF 600, then RBF 660 for many years. Now trying the Motul RBF 700. Higher dry boiling point than Motul 5.1. It helps prevent brake fade when turning fast laps on a bike on a roadracing track. I've also used it (with great success) in the race cars I've worked on, which have full carbon brakes.
Always keep brake fluid fresh for optimum performance.
Always keep brake fluid fresh for optimum performance.
This has been mentioned before, but worth repeating here. The difference between wet and dry boiling point is important if you don't flush the brake system regularly. Many DOT4 fluids have a higher dry boiling point, yet a lower wet boiling point, compared to DOT3. DOT 3 and 4 are miscible, so if your car allows either, you might be better off using DOT3 if you only flush the system every couple of years.
the little race cars you work on go 300mph and even with a parachute(s) need all the braking power they can get
